Amongst multicarrier communication schemes, the OFDM (Orthogonal Frequency Division Multiplexing) communication scheme has attracted attention as a high-speed transmission technique that reduces the influence of frequency selective fading caused by multipath channels, compared to single carrier communication schemes.
In cellular systems such as mobile phone systems, cell search technique, in which a mobile station searches for the optimal base station to connect the radio link to, upon starting communication, upon handover, upon waiting communication during discontinuous reception, and so on, is one of significant functions.
Non-Patent Document 1 discloses conducting cell search in the following three steps. In the first step, correlation detection is performed with respect to the first synchronizing sequence (P-SCH: Primary Synchronization Channel) in the time domain. This detects the OFDM symbol timing and subframe timing.
In the second step, correlation detection is performed with respect to the second synchronizing sequence (S-SCH: Secondary Synchronization Channel) in the frequency domain. This detects, for example, a cell ID group, radio frame timings, a cell structure, a MIMO antenna structure and a BCH bandwidth.
In the third step, correlation detection is performed with respect to the common pilot channel in the frequency domain. To be more specific, correlation between a replica of common pilot signal and a received signal after an FFT is detected. This detects a cell ID belonging to a cell ID group detected in the second step and identifies the sector number.
As described above, by detecting the correlation between the replica signal of the synchronization channel (SCH) held in a receiving apparatus and the received signal, a timing can be detected.    Non-Patent Document 1:3 GPP, R1-060780, NTT DoCoMo, NEC, “SCH Structure and Cell Search Method for E-UTRA Downlink”